The present invention relates to the transportation in a sterile atmosphere of human beings who, for medical reasons, have to be confined in a sterile atmosphere and transferred from one place to another within the same hospital, or even over a distance of several dozen or hundred kilometers, which consequently involves transportation in an autonomous vehicle (aircraft, helicopter, car), without there being any break in the seal and sterility of the medium in which they are housed, whereby it is impossible to give them even emergency medical treatment. This is particularly the case with persons who have, at least temporarily, lost all or part of their immunological defences, as well as certain premature babies, who often have to travel long distances to ensure appropriate survival treatment.
In the case of babies, which represent the preferred, but non-exclusive field of application of the invention, it is necessary to use incubators which must theoretically protect these babies against three essential factors, namely bacterial contamination, relative humidity and temperature. Experience has unfortunately shown that the protection which is actually obtained against these three factors is very illusory for the reasons indicated hereinafter.
With regards to bacteriological contamination, the confinement offered by an incubator, which is really only an enclosure sealed by a cover, is not tight because any intervention on the baby involves the opening of the enclosure. This in itself limits to the absolute minimum any intervention during transportation, whilst it is necessary to sterilize the interior of the vehicle in which transportation takes place, which may be impossible and certainly cannot take place rapidly, when there is a need for emergency transportation.
Certain babies require a higher than normal relative humidity from the pulmonary standpoint. They may also require an ambient temperature of up to 37.degree. C. A combination of these two physical conditions provides a climate which is particularly favourable for bacterial growth.
With regards to the temperature, relatively sudden variations often occur in incubators, even when they are thermostatically controlled, because the need to open the cover a certain number of times on each occasion involves an inflow of a by no means negligible volume of fresh air, which causes a sudden temperature drop. In certain cases, these variations can be very unpleasant for the baby (stress phenomenon).
In connection with medical intervention in a fixed station and with a confined atmosphere, isolators are also known, which make it possible to completely biologically separate a patient from the exterior, whilst communicating with him in both directions (introduction and removal of objects or equipment) with the aid of tight transfer or intervention devices, such as gloves and the like, whilst others can at least partly form an integral part of the enclosure wall. An enclosure of this type is generally ventilated by an air circuit between an inlet and an outlet, each of which has an absolute filter, which stops the entry or exit of any bacteria. Whenever necessary, such an enclosure with its filters can be very easily sterilized by a microbicidal agent circulating in the ventilation circuit for a certain period, such as e.g. peracetic acid.
Such isolators and their intervention devices have been described, particularly on pp.121 to 125 of No. 284 of the Feb. 1979 issue of the Journal Labo Pharma, pp.227 to 230 of Vol.3 of the 1978 edition of Science et Techniques des Animaux de Laboratoires, as well as French Pat. No. 8,003,067, filed on Feb. 12 1980 by the Applicant Company.
Consideration can obviously be given to the use of such isolators for transporting human beings in a sterile atmosphere, but almost immediately a virtually insurmountable difficulty is encountered, namely that of the heating power for such an isolator operating in open circuit. Thus, experience has shown that to heat and maintain at around 37.degree. a human isolator in an ambient of 20.degree. C. and traversed by a fresh air flow of 10 m.sup.3 /h, it is necessary to have an electrical power of 680 W and approximately 90 minutes are required to raise the temperature. Although this can be achieved easily for a fixed station use, where electrical mains are available, it is difficult to realise on board a vehicle through the use of a conventional accumulator battery, even if the latter is permanently recharged by the vehicle alternator. It must be borne in mind that such transportations frequently take place in emergencies using vehicles of the ambulance type which, by their very nature, are large energy consumers, not only for heating, but also for headlights, revolving lights and sirens. Even when the accumulator batteries of such vehicles are supplied by a dynamo or alternator connected to the engine, they have a tendency to rapidly discharge and could not therefore ensure a transportation lasting several hours, whilst supplying such a high complementary power.